This work demonstrates that a quantum temporal field can generate genuine Bell entanglement between spatially separated localized modes. By defining two orthogonal, well-localized modes and introducing a parametric two-mode interaction, we produce a two-mode squeezed vacuum state. Through heralding or unitary processing, the system can be projected into an effective single-excitation Bell state. Measurement correlators are computed, showing explicit violation of the CHSH inequality while preserving no-signalling. This provides a field-theoretic realization of quantum correlations directly from the temporal field framework, linking abstract temporal dynamics to concrete quantum information phenomena.
This work demonstrates that a quantum temporal field can generate genuine Bell entanglement between spatially separated localized modes. By defining two orthogonal, well-localized modes and introducing a parametric two-mode interaction, we produce a two-mode squeezed vacuum state. Through heralding or unitary processing, the system can be projected into an effective single-excitation Bell state. Measurement correlators are computed, showing explicit violation of the CHSH inequality while preserving no-signalling. This provides a field-theoretic realization of quantum correlations directly from the temporal field framework, linking abstract temporal dynamics to concrete quantum information phenomena.
In this paper we investigate the quantum decoherence and the dynamics of nonlocality of two-mode single-photon subtracted squeezed vacuum state(TSSV).We numerically calculate the relative entropy of the entanglement and analyze in detail the linear entropy of the entanglement.Then we calculate the Bell-CHSH inequality based upon pseudospin operators and find that the Bell inequality is always violated.Therefore,we are sure that the decoherence can only decrease the amount of the entanglement but can not eliminate the entanglement of TSSV completely.
It is one of the most remarkable features of quantum physics that measurements on spatially separated systems cannot always be described by a locally causal theory. In such a theory, the outcomes of local measurements are determined in advance solely by some unknown (or hidden) variables and the choice of local measurements. Correlations that are allowed within the framework of a locally causal theory are termed classical. Typically, the fact that quantum mechanics does not always result in classical correlations is revealed by the violation of Bell inequalities, which are constraints that have to be satisfied by any classical correlations. It has been known for a long time that entanglement is necessary to demonstrate nonclassical correlations, and hence a Bell inequality violation. However, since some entangled quantum states are known to admit explicit locally causal models, the exact role of entanglement in Bell inequality violation has remained obscure. This thesis provides both a comprehensive review on these issues as well as a report on new discoveries made to clarify the relationship between entanglement and Bell inequality violation. In particular, within the framework of a standard Bell experiment, i.e., a Bell inequality test that is directly performed on a single copy of a quantum state r, we have derived two algorithms to determine, respectively, a lower bound and an upper bound on the strength of correlations that r can offer for any given Bell inequality. Both of these algorithms make use convex optimization techniques in the form of a semidefinite program. By examples, we show that these algorithms can often be used in tandem, in conjunction with convexity arguments, to determine if a quantum state can offer nonclassical correlations and hence violates a given Bell inequality. On the other hand, since a standard Bell experiment typically involves measurements over many copies of the quantum systems, we have also investigated the possibility of enhancing the strength of nonclassical correlation by, instead, performing collective measurements on multiple copies of the quantum systems. Our findings show that even without postselection, such joint measurements may also lead to stronger nonclassical correlations, and hence a better Bell inequality violation. Meanwhile, previous studies have indicated that entangled state admitting locally causal models may still lead to observable nonclassical correlations if, prior to a standard Bell experiment, the state is subjected to some appropriate local preprocessing. This phenomenon of hidden nonlocality was discovered more than a decade ago, but to date, it is still not known if all entangled states can demonstrate nonclassical correlations through these more sophisticated Bell experiments. A key result in this thesis then consists of showing that for all bipartite entangled states, observable nonclassical correlations, in the form of a Bell-CHSH inequality violation, can indeed be derived if we allow both local preprocessing and the usage of shared ancillary state which by itself does not violate the Bell-CHSH inequality. This establishes a kind of equivalence between bipartite entanglement and states that cannot be simulated by classical correlations. In summary, for a standard Bell experiment where no local preprocessing on a quantum state r is allowed, we have provided two algorithms that can be used in tandem to determine if r can be simulated by a locally causal theory, whereas in the scenario where local preprocessing is allowed, we have demonstrated that bipartite entangled states are precisely those which cannot always be simulated classically.
We present a reformulation of quantum entanglement and Bell-type correlations based on a dynamically emergent temporal structure defined by a future-directed vector field Φμ(x). This intrinsic temporal flow induces a physical foliation of spacetime, enabling a causal, local, and covariant account of quantum correlations. Within this framework, entangled states are described as topologically and causally coherent field configurations, and Bell inequality violations arise without requiring acausal nonlocality. Our results suggest a new geometric foundation for quantum nonlocality rooted in the spontaneous symmetry breaking of temporal order.
In the Cosmology of the Quarkbase, quantum particles and photons are interpreted as excitations of an etheric plasma represented by the scalar or vector field Ψ(x,t). An experiment that, in standard quantum theory, produces an entangled pair instead generates in this framework a single non-local field excitation: a coherent combination of Ψ-modes correlated through conservation of momentum, spin, and polarization, as well as through the coupling topology between local sources (quarkbases). Local measurement acts as a projection on this extended excitation, producing the experimentally observed strong correlations without any exchange of causal signals between detectors. The Quarkbase formalism introduces explicit medium parameters —density ρp, compressibility K, and effective mass mΨ— that define physical scales such as the screening length λ = 1/mΨ. These quantities determine the spatial decay of entanglement visibility according to V(r) ∝ e⁻ʳ/λ / r, and the effective CHSH parameter becomes Seff = C(r) 2√2. Therefore, if the vacuum possesses a finite λ, Bell-type correlations should attenuate exponentially with distance, providing a falsifiable signature of a massive or screened etheric field. Mathematically, the framework reproduces the predictions of quantum field theory —Bell states, coincidence probabilities, CHSH violation— while offering an ontological interpretation in which entanglement arises from the geometry and coherence of the Ψ-field rather than from instantaneous nonlocal action. The theory therefore unifies microscopic quantum behavior with macroscopic medium dynamics, transforming questions about “collapse” and “nonlocality” into experimentally testable properties of the underlying ether-plasma.
We investigate the internal-state Bell nonlocal entanglement dynamics, as measured by CHSH inequality of two atoms interacting with a vacuum multi-mode noise field by taking into account the spatial degrees of freedom of the two atoms. The dynamics of Bell nonlocality of the atoms with the atomic internal states being initially in a Werner-type state is studied, by deriving the analytical solutions of the Schrödinger equation, and tracing over the degrees of freedom of the field and the external motion of the two atoms. In addition, through comparison with entanglement as measured by concurrence, we find that the survival time of entanglement is much longer than that of the Bell-inequality violation. And the comparison of the quantum correlation time between two Werner-type states is discussed.
Entanglement, describing the inseparability of a quantum multiparty system, is one of the most intriguing features of quantum mechanics. Violation of Bell inequality, for ruling out the possibility of local hidden variable theories, is commonly used as a strong witness for quantum entanglement. In previous Bell test experiments with photonic entanglement based on two-photon coincidence measurement, the photon temporal wave packets are absorbed completely by the detectors. That is, the photon coherence time is much shorter than the detection time window. Here we demonstrate generation of frequency-bin entangled narrowband biphotons, and for the first time, test the Clauser-Horne-Shimony-Holt (CHSH) Bell inequality |S|<= 2 for their nonlocal temporal correlations with time-resolved detection. We obtain a maximum |S| value of 2.52+/-0.48 that violates the CHSH inequality. Our result will have applications in quantum information processing involving time-frequency entanglement.